This invention pertains to an improvement in the treatment of autoimmune diseases. More specifically, the invention is directed to the administration of autoantigens and biologically active fragments or analogs of such autoantigens in aerosol form for the prevention and therapeutic treatment of autoimmune diseases. The invention also includes aerosol formulations of autoantigens useful in the treatment of autoimmune diseases in mammals.
Autoimmune diseases are characterized by an abnormal immune response involving either cells or antibodies, that are in either case directed against normal autologous tissues.
Autoimmune diseases in mammals can generally be classified in one of two different categories: cell-mediated disease (i.e. T-cell) or antibody-mediated disorders. Non-limiting examples of cell-mediated autoimmune diseases include multiple sclerosis, rheumatoid arthritis, autoimmune thyroiditis, diabetes mellitus (Juvenile onset diabetes) and autoimmune uveoretinitis. Antibody-mediated autoimmune disorders include myasthenia gravis and systemic lupus erythematosus (or SLE).
The current treatments for both categories of autoimmune diseases involve administration of drugs which non-specifically suppress the immune response. Examples of such drugs are methotrexate, cyclophosphamide, Imuran (azathioprine) and cyclosporin A. Steroid compound such as prednisone and methylprednisilone are also employed in many instances. These drugs have limited efficacy against both cell- and antibody-mediated autoimmune diseases. Use of such drugs is limited by virtue of their toxic side effects and also because they induce "global" immunosuppression in a patient receiving prolonged treatment with the drug, e.g. the normal protective immune response to pathogenic microorganisms is downregulated thereby increasing the risk of infections caused by these pathogens. A further drawback is that there is an increased risk that malignancies will develop in patients receiving prolonged global immunosuppression.
Other therapies have been proposed for the treatment of autoimmune diseases. U.S. patent application Ser. No. 65,794 filed Jun. 24, 1987 (now abandoned) and copending International Patent Application PCT/US88/02139 filed Jun. 24, 1988, disclose that the oral or enteral administration of relatively high levels of myelin basic protein (MBP) and disease-inducing and non-inducing fragments and analogs thereof is effective in suppressing acute monophasic experimental allergic encephalomyelitis (EAE), an induced T-cell-mediated autoimmune disease directed against myelin basic protein. EAE is a recognized and widely used animal model for multiple sclerosis (MS). The above-identified applications also disclose that the oral or enteral administration of Mycobacterium tuberculosis is an effective treatment for suppressing adjuvant arthritis and extrapolate the aforementioned results to the treatment of other autoimmune diseases.
Copending U.S. patent application Ser. No. 379,778 filed Jul. 14, 1989 discloses the oral or enteral administration of S-antigen for the treatment of autoimmune uveoretinitis.
Various methods have been employed to induce antigen-specific suppression of EAE such as immunization with MBP emulsified in incomplete Freund's adjuvant (Lando, Z. et al., J.P. Immunol., 126: 1526, 1981), or an intravenous injection of MBP coupled to lymphoid cells (Sriram, et al., Cell Immunol. 75: 378, 1983).
Traugott et al., J. Neurol. Sci. 56: 65-73, 1982 and Raine et al., Lab. Investigation 48: 275-84, 1983 teach that treatment of a strain of guinea pigs suffering from chronic relapsing EAE by parenteral administration of MBP alone or, in incomplete Freund's adjuvant (IFA) or, in combination with galactocerebroside, a lipid hapten of myelin, suppressed the clinical symptoms of EAE.
Based on an English language abstract, Belik et al., Vopr. Mev. Khin. 24: 372-377, 1978, disclose the parenteral administration of "alkaline myelin protein fragment (AMPF)" and "synthetic encephalitogenic peptide (SEP)" to guinea pigs with EAE. The animals had been sensitized by bovine AMPF or synthetic SEP but recovered after administration of AMPF.
Braley-Mullen et al., Cell Immun. 51: 408, 1980, disclose the suppression of the symptoms of experimental autoimmune thyroiditis in guinea pigs by injection of thyroglobulin antigen in IFA.
Nagler-Anderson et al., Proc. Natl. Acad. Sci. USA 83: 7443-7446, 1986 disclose the oral administration of collagen to suppress collagen-induced arthritis in a mouse model. Type II collagen-induced arthritis was suppressed in the mouse by intragastric administration of soluble, but not denatured, Type II collagen prior to immunization of the animal with Type II collagen in an adjuvant. The Nagler-Anderson antigen was not administered in aerosol form.
Other investigators have examined the effects of aerosolized proteins on the treatment of genetic diseases and on modulating the IgE response in mammals.
Hubbard, R. C. et al. (Proc. Natl. Acad. Sci. (USA) 86: 680-684, 1989) demonstrated the feasibility of administered proteins to mammals in aerosol form. Hubbard et al. disclose administration of a relatively large protein alpha.sub.1 -antitrypsin (AAt) via the pulmonary epithelial surface for the treatment of alpha anti-trypsin deficiency, an inherited genetic disease. AAt, a 45,000 dalton molecular weight single-chain polypeptide (that functions as an inhibitor of neutrophil elastase) was administered to sheep in an aerosol form. Aerosolized AAt remained fully functional and intact in the tissues of the mammal to which the material was administered and diffused across the alveolar epithelium, as evidenced by the presence of AAt in the lung, lymph and blood tissue.
Holt, P. G. et al., Immunol. 42: 409-417, 1981 disclose the inhibition of specific IgE responses in mice by pre-exposure to inhaled antigens. The exposure of mice to aerosolized ovalbumin once weekly for seven weeks caused the suppression of IgE responses when these animals were challenged intraperitoneally with Soluble or alum-precipitated ovalbumin.
Sedgwick, J. D. et al., Immunol. 56: 635-642, 1985 reported on the down-regulation of the specific IgE response to an inhaled antigen. Repeated exposure of rats to an aerosol of ovalbumin induced carrier-specific tolerance to subsequent challenge with the same antigen.
Holt, E. G. et al., Immunol. 60: 97-102, 1987 disclose that repeated inhalation of low levels of ovalbumin by mice or rats preferentially induced tolerance to the IgE antibody class and postulated that this process represented an important protective mechanism that normally prevents allergic sensitization of a mammal to air-borne antigens.
Sedgwick, J. D. et al., Cell Immunol. 94: 182-194, 1985 disclose that the repeated exposure of high-IgE-responder rats to an aerosol of an antigen once weekly triggered progressively increasing levels of antigen-specific IgG in the serum. Adoptive transfer of splenocytes from aerosol-exposed animals to naive rats caused a suppression of IgE responses without affecting specific IgG responses.
No method or technique for treating or preventing autoimmune diseases is suggested or disclosed in these references. It is an object of the present invention to provide methods for treating mammals suffering from autoimmune diseases.
Another object of the present invention is to provide pharmaceutical formulations for treating mammals suffering from autoimmune diseases.
A still further object of the invention is to provide a formulation for administration to mammals for the purpose of preventing or treating autoimmune diseases in such mammals.